Interludes - how often is too often?

Hey all, I've just finished the first draft of my 500+ page novel. The novel includes 83 5-7 page chapters. To include backstory and world building, I included an interlude approximately every 10 or so chapters. I made sure that the chapter before the interlude ended somehow leading into the interlude itself.

My story involves a cast of 8 people, which I use the interludes to flesh them out and why they are acting and making decisions in such ways.

How many interludes is too much? Or does it relate to how they fit into the entire story while keeping the plot connected and the reader intereated?